Fiber optic cables are frequently used for interconnecting computer systems (e.g., servers) because these cables can simultaneously carry a large amount of data without excessive transmission loss. A trunkline is a type of fiber optic cable that typically includes multiple optic fibers and strength filaments (e.g., Kevlar yarns) arranged lengthwise and encased in a protective jacket (e.g., plastic or metal tubing). At each end of the trunkline, the optic fibers are furcated into individual cables that terminate at individual connectors.
One conventional technique for furcating the trunkline uses heat-shrink tubing and epoxy. FIG. 1, for example, illustrates a prior art furcated cable 100 having a furcation unit 101 with a heat-shrink tube 102 encasing an epoxy 104, a trunkline 106 connected to one end of the furcation unit 101, and furcation tubes 112 projecting from the other end of the furcation unit 101. The trunkline 106 includes a cable jacket 113 encasing portions of optic fibers 108 and cable filaments 110. Each furcation tube 112 includes a tube jacket 116 encasing tube filaments 114 and one of the optic fibers 108. The heat-shrink tube 102 overlaps both the trunkline 106 and the furcation tubes 112 to enclose a portion of the optic fibers 108 and filaments 110, 114. The epoxy 104 rigidly binds the enclosed optic fibers 108 and filaments 110, 114 inside the heat-shrink tube 102. Each optic fiber 108 extends from the trunkline 106, through the epoxy 104, and out from the furcation tubes 112.
There are a number of drawbacks associated with the cable 100 described above. First, the furcation tubes 112 can occupy a considerable amount of space inside the heat-shrink tube 102 such that the heat-shrink tube 102 may not be able to accommodate a large number of furcation tubes. Furthermore, the optic fibers 108 can easily be damaged during installation, manufacturing, and other handling processes. For example, installing the furcated cable 100 typically includes pulling on the cable jacket 113 to draw the trunkline 106 through cable trays, conduits, and other channelways. The furcation unit 101 transmits the pulling force directly to the optic fibers 108 because the epoxy 104 rigidly binds the optic fibers 108 to the cable jacket 113. The transmitted force can damage the fragile optic fibers 108.
Another conventional technique for furcating the trunkline uses insertion-type connectors, such as the UniCam® MTP® connectors manufactured by Corning Cable Systems of Hickory, N.C. One drawback associated with this type of connectors is insertion loss. For example, a 10-gigabit system today typically has a transmission-loss budget of about 2.8 dB. An insertion-type connector typically incurs approximately 0.5 dB to 1.0 dB transmission loss at each junction. As a result, using three insertion-type connectors can potentially exceed the transmission loss budget.